This is an explanation of the world: everything that takes place is due to the combination of ksetra and ksetrajna, the body and the spirit soul. This combination of material nature and the living entity is made possible by the Supreme God Himself. The mahat-tattva is the total cause of the total cosmic manifestation, and because in the total substance of the material cause there are three modes of nature, it is sometimes called Brahman. The Supreme Personality impregnates that total substance, and thus innumerable universes become possible. This total material substance, the mahat-tattva, is described as Brahman in the Vedic literature: tasmad etad brahma nama-rupam annam ca jayate. Into that Brahman the seeds of the living entities are impregnated by the Supreme Person. The twenty-four elements, beginning from earth, water, fire and air, are all material energy, called Maha-brahman, or the great Brahman, the material nature. As is explained in the Seventh Chapter, beyond this there is another, superior nature-the living entity. In material nature the superior nature is mixed by the will of the Supreme Personality of Godhead, and thereafter all living entities are born of this material nature.